A three-dimensional video display device that displays a video displayed in a two-dimensional video display device as a three-dimensional video using a mirror assembly including a plurality of half mirrors has been known. For example, a three-dimensional video display device which is suggested in this invention is disclosed in Patent Document 1. In other words, using a mirror device having a plurality of mirrors (half mirrors and total reflection mirror) which are inclined on a screen of the two-dimensional video display device toward an observer at a predetermined angle and disposed at a predetermined interval in a depth direction, in a screen of the two-dimensional video display device, a plurality of virtual image generating regions that generate virtual images by the mirrors in a position of the mirror and virtual image non-generating regions that do not generate a virtual image between the virtual image generating regions are formed, and an image displayed in the virtual image generating region is reflected by a corresponding mirror to be displayed as a three-dimensional video at an observer side.
Further, a similar three-dimensional video display device is also disclosed in Patent Document 2. Most of all, in Patent Document 2, it is disclosed that when information is displayed in each display region of the display screen which is divided into (N+1) regions, an enlargement/reduction controller 105 controls the enlargement or reduction of a display size at which the information is displayed (size of the display region).